big turbo, low boost, HELP!

[Rob1]

So on my 89 supra turbo, previous owner upraded to a T61 turbo, not sure what brand, and the car is( well was before i disconected ecu lol) pretty fast.

so i hooked up a temporary boost gauge and ran it through the passengerside window to see what i am pushing.

If im not mistaken, disconecting the waste gate line from the charge pipe will alow for maximum boost because the waste gate stays closed under a boost right?

So with waste gate hooked up i was getting around 7 psi and unhooked i was getting about 7.5 maybe 8 pounds of boost. correct me if m wrong but stock they run 8 right? so why the low boost?

I checked the turbine shaft and there was very very little if any play in it so i think the turbo is fine but why such low psi? any advice appreciated.